


Sharpen Your Knife

by Anonymous



Category: Haikyuu!!
Genre: Additional Warnings In Author's Note, Aged-Up Character(s), Alpha/Alpha, Alpha/Beta/Omega Dynamics, Alternate Universe - Alien Invasion, Anal Sex, Dirty Talk, Eventual Romance, Getting Together, M/M, Power Dynamics, Rough Sex, Sexual Tension
Language: English
Status: In-Progress
Published: 2018-09-03
Updated: 2019-06-06
Packaged: 2019-07-02 19:52:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 9,052
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15803448
Author URL: https://archiveofourown.org/
Summary: The world is ending. Iwaizumi and Oikawa find reasons to fight in each other.





	1. Chapter 1

**Notes for the Chapter:**

> Note: I don’t like conventional A/B/O fics and decided that if I’m going to write one, it’s not going to be your usual affair. I took the premise of A/B/O and sort of ran with it so some of the ideas in this fic might not be very common in other omegaverse fics (I don’t know, I don’t read a lot of them). Also, XCOM references left and right.
> 
> EXPANDED TAGS: anal sex (first time anal, switching/versatile, penetration with fingers and penis, unprotected sex), rough sex (general rough sex, biting, spanking during sex, power dynamics, roughness with underlying gentleness), dirty talk (general dirty talk plus banter mixed in with the idea of power dynamics)

You think with the fall of society that the social hierarchy of classes and stigma surrounding them would fall as well. You’d be wrong.

When the aliens turned on the humans after one hundred years of peace and prosperity, all humans had to cling to were their stupid rules. Otherwise, they were no more than the animals the aliens claimed they were. So humans fought and dug their way underground to fight for another day, and clung to the rules of a society in ruins.

One of those stupid rules is that two alphas together is wrong.

Oikawa really doesn’t give a damn what others alpha chose to do together. Why should he? They’re all just trying to survive. If two people want to fuck consensually, Oikawa isn’t going to stop them, not when each day could be their last.

He doesn’t get it, though. Doesn’t get how an alpha can bear to smell the sharp scent of another alpha’s sweat and pheromones. Oikawa can hardly bear the stench of the gym where all of the soldiers work out. There are more alphas in Special Ops than in any other department and they reek something foul when they lift weights and run on treadmills like they have something to prove.

During his lunch break, he sits at his desk and reviews the latest report from the Kuroo in the Engineering Department. He needs to know how far along they are on their nanobot project. The bots may be just the tool he needs to finally make some real progress on his genetic engineering work. Kuroo jokingly calls it Project Superman.

If they can alter the human body, they can give humans the capabilities to finally do some real damage to the enemy…

The swish of the door opening brings his nose up out his report. The turn of cart wheels makes his palms sweat with excitement. The unfamiliar face pulling the cart into his lab makes him frown with confusion.

The man is definitely not a new addition to Oikawa’s team of scientists or he would have heard about it. His ID tag is too far away for Oikawa to see the symbol denoting his department and his attire doesn’t give much away, either, a neutral colored long sleeve shirt and dark cargo pants.

Doesn’t really matter who he is. Oikawa is far more interested in what’s on the cart than who’s pulling it.

“Is this the Xenophile’s Lair?” the man asks.

Oikawa sighs. “This is the Xeno-Morgue, yes. Are those bodies from the last mission? Which squad brought them in?”

“Tau Squad.”

Oikawa stands up and walks over, taking the cart from the man and spotting three corpses: two Sectoids and a Thin Man. “Why the hell are different species touching?”

The man doesn’t say anything, just frowns slightly in confusion, clearly unsure why that’s an issue and how this is his fault and what he’s supposed to say. Oikawa knows what that look means because he sees it a lot. People outside of the Science Department just don’t _get_ it.

He grabs the cart from the man and begins to push it further into his office to clean up this mess before his samples become more contaminated, but the man grabs his wrist. His grip is surprisingly strong, not something Oikawa could easily shake out of.

“I was told to take this to the Xenophile’s Lair,” the man says with the obedience of a good soldier, or a dog. “You said this was—what the hell did you call this place?”

“The Xeno-Morgue. The Xenophile’s Lair is what the squaddies call my office. It’s a joke, though it’s not a very good one. Now, are you going to give me my specimens or not?”

The man raises his hands into the air in a clear “don’t shoot the messenger” pose.

Oikawa sighs as he drags the cart deeper into his office. Tau is a sniper squad. Usually they get more corpses than this. He figures it’s a good thing if they got in and out without trouble. Good for them, at least. Oikawa’s job is to dissect aliens and figure out how to weaponize their own anatomy against them. He can’t do that without specimens to examine.

He pushes the cart into the autopsy room, a large room with a dozen silver slick tables and glass walls, deciding he will deal with the corpses after lunch. For now, he puts on a pair of gloves and easily moves the corpses onto their own tables to prevent any further contamination between species and specimens. When he’s done, he snaps off his gloves and puts them in the red biohazard bag.

When he comes back into his main office, he’s surprised the delivery boy is still there. Maybe boy isn’t quite the right word to describe the man standing awkwardly near the entrance. He looks to be around Oikawa’s age, well built with gorgeously tan skin and sharp brown eyes and cheeks bones that make even Oikawa jealous. It’s clear he’s a soldier from his posture and demeanor. The question is whether he’s Special Ops or your run of the mill foot soldier.

“You’re new, aren’t you?” Oikawa says, sitting back down at his desk. He moves the report from Engineering aside in favor of actually eating for a change.

“I’m Iwaizumi Hajime, assault class. I just got transferred here to help fill out a new squad.”

“Zeta Squad?” Oikawa guesses. That’s the only new squad he’s heard about in the interdepartmental memos.

Iwaizumi nods.

Special Ops, then.

Oikawa hums and begins to unpack his standard-issue meal bar. It has all the protein, carbs, and vitamins humans need to survive and it tastes about as good as shit.

“They sent you down here to haze you, you know,” Oikawa says lightly. “It’s what they do with all the rookies.”

Oikawa looks up and sees Iwaizumi just standing there, back straight, expression neutral, and eyes locked on Oikawa.

“I’m not a rookie,” Iwaizumi says in a practiced neutral tone. Oikawa bets it’s the same tone he uses when accepting an order he doesn’t like. “I’m a Lieutenant.”

“You’re new to this base. You’re a rookie in their eyes.” Oikawa smiles, all false pleasantry. “I bet they told you all sorts of things about me to try and scare you before sending you down here. Did they tell you I would strap you to a table and take samples from you, or did they tell you would drug you and probe you? You can tell me what they called me, too. I won’t get mad—pinky promise.”

Iwaizumi doesn’t look like he believes Oikawa’s pleasant smile for a second. “I don’t think this is appropriate.”

“Xenophile? Alien lover?” No reaction. Oikawa hums and leans back in his chair, stretching out his legs and crossing his ankles on top of his desk. That gets a reaction, a subtle shift in posture. If Oikawa didn’t know any better, he would say that Iwaizumi was reacting to seeing his legs stretched out. “Well? What did they call me?”

Iwaizumi holds his gaze when he says, “Alien Fucker. I don’t know if they meant you fuck aliens, or you’re a just a fucker that works with them. They didn’t specify.”

This new Lieutenant plays along better than most. Squaddies are either terrified of him, hate him, refuse to acknowledge his position, or some combination of the above. Half of them are alphas with egos as large as their heads and they hate the idea of another alpha being smarter than them. Alpha squaddies are always challenging each other, trying to prove their dominance, but they’ll get written up for attacking Oikawa, who’s in another department, so they can’t do shit against him.

Here in the lab, Oikawa is the true alpha and they can’t stand it.

“You can go now,” Oikawa says dismissively with the same overly pleasant smile. “Thanks for the delivery.”

Iwaizumi moves to leave but pauses at the door, looking back over his shoulder. What he asks surprises Oikawa. Hell, the fact that he didn’t run for the hills surprises him more.

“What did you say your name was?”

“I didn’t.” Oikawa pauses. “I’m Dr. Oikawa Tooru, head of the Science Department.”

 

* * *

 

Oikawa makes his way to the Engineering Department two floors down at the end of the week, Kuroo’s report tucked under his arm, the pages marked to hell with questions and comments. It’s the monthly Demo Day when all of the department heads gather to watch the Engineering Department demonstrate their newest inventions.

Oikawa arrives in the Observation Deck that overlooks the Demo Ground. There are a dozen soldiers separated into small groups talking and laughing. Some are wearing their standard tactical gear, others decked out in new versions of armor Oikawa recognizes from memos. Amongst them, Oikawa spots Iwaizumi, laughing with another man.

The dozen soldiers down there must be the newly formed Zeta Squad, the latest project of Special Ops. They’re meant to be the best of the best. The fastest, the strongest, the best shots. Oikawa thinks they may all be alphas, who tend to have heightened senses when the adrenaline starts pumping.

Kuroo is busy talking to several other members of his team, each holding a tablet and wearing a headset connected to the speaker system. Oikawa goes around and makes pleasantries with the other heads of departments and by the time he’s done, Kuroo is finished with his teammates and comes to stand next to Oikawa as he gazes out of the large glass window to the Demo Ground below.

“What’d you think?” Kuroo asks, tapping the file under Oikawa’s arm.

“It’s good progress,” Oikawa says. “The _in vitro_ work is promising. A few more replicates and I think we can move to _in vivo_.”

“Sweet. I love testing how many tiny weights mice can drag. It’s fucking hilarious.”

Oikawa laughs. “So, what are we testing today?”

“Zeta Squad, for starters,” Kuroo says with a grin. “This is the first time they’re being shown to all the department heads. Only Special Ops has seen them all together.”

“I bet Special Ops is eager to pimp them out.”

Kuroo hums non-committedly, not wanting to say it out loud. He isn’t a department head like Oikawa. If he’s overheard, he could get in trouble.

“They hazed one of the transfers by sending him to my morgue earlier in the week. They’re calling me Alien Fucker now, apparently.”

“You should have told me which ones called you that. I decided which squaddies were wearing the proto armor this time.”

In project demos, wearing prototype armor means being beat up and shot at.  

“My knight in shining armor,” Oikawa says sarcastically, pretending to swoon, a hand to his chest and his grin teasing. Kuroo laughs.

When the head of Special Ops walks in flanked by his two Majors, they get started. The head of Special Ops, an old man named Ukai, is given a headset and a tablet.

“Zeta Squad, fall in and await orders,” Ukai commands, his voice leaving no room for argument or question.  

Like damn dogs, the soldiers line up side to side. There’s twelve in total, ten men and two women, a mix of soldier classes from assault and heavy to support and snipers.

Out of the floor of the Demo Grounds rises a table with several guns.

“Pick up the weapon next to your ID number then fall back in line,” Ukai orders.

The soldiers approach the table, each taking one weapon and looking them over for the first time to test how they feel. They’ll each write feedback at the end which will be used to optimize the weapons. Once the weapons pass all tests and the soldiers don’t complain too much, engineering starts turning them out, same with armor.

Ukai jerks his chin towards Kuroo.

Kuroo looks down at his tablet then turns on his headset. “Iwaizumi, you’re holding the second version of our plasma rifle. This weapon is designed for support and assault classes like yourself. This modified rifle fires a jet of ionized gas through a focused magnet field.”

As Kuroo talks, on the other end of the Demo Ground, five ballistic dummies and several metal planes intended to mimic cover scene out in the field rise from the floor. Three of the dummies are out in the open, easy targets for a good shot, while the other two are hidden between the metal planes, only partially visible.

“We designed this rifle to by highly efficient and a deadly primary weapon,” Kuroo goes on. “In the first version, soldiers complained about the kick back. We’ve made modifications to reduce the kick back without reducing power. If you could please shoot—”

Before Kuroo can even finish the order to shoot the dummies, Iwaizumi has raised the gun and shot the nearest dummy in the head. He turns his body, aims for the next, and hits. Turn, hit.

Kuroo turns off his headset and grumbles to Oikawa, “Fucking trigger-happy squaddies.”

Oikawa hums in agreement and watches as Iwaizumi shoots the two dummies half-guarded by the metal planes with ease. He doesn’t get headshots, but he gets clear body shots.

“He’s a good shot,” Kuroo concedes quietly.

Oikawa hums again, not wanting to admit it and not sure why he cares.

Ukai looks at Kuroo. “Next round.”

“Yes, Sir,” Kuroo replies smoothly, reaching down and tapping at his tablet. More dummies and more obstacles appear on the Demo Ground floor.

One by one, Iwaizumi shoots them down, never missing a shot.

 

* * *

 

Oikawa is eating lunch in the Mess Hall with his team when Iwaizumi comes and sits between Kindaichi and Kunimi without warning, squeezing himself into the small space the two left between them to give some sort of illusion that they aren’t together, like it fools anyone. Matsukawa and Hanamaki stare at Iwaizumi while Kindaichi hastily moves to make room and Kunimi remains rooted, refusing to budge for some stranger.

“Are you supposed to be acting on a dare or something?” Hanamaki asks from Oikawa’s left. It wouldn’t be the first time.

From Oikawa’s other side, Matsukawa tosses an arm around Oikawa’s shoulders and presses their temples together. “Because this guy doesn’t look like much with his pretty face and tight rear—"

“Are you complimenting me or insulting me?” Oikawa asks, offended.

“—but he can probably kick your ass.”

Iwaizumi arches an eyebrow and grins at Oikawa, his dark eyes solely on him. “Well, can you?”

“Can I  _what_?” Oikawa replies calmly, wondering where this heat is coming from inside his body.

“Kick my ass?”

Matsukawa pulls away from Oikawa and breaks out into laughter with Hanamaki.

On one hand, Iwaizumi is a trained soldier, a killer, an alpha. On the other hand, Oikawa is an alpha too and his pride forbids him from admitting defeat.

“Why would you even want to sit with us?” Oikawa asks instead, dodging the question.  “Why aren’t you with your squad?”

Iwaizumi shrugs. “I see them all the time. Can’t a guy be friendly with his colleagues for an hour?”

“Squaddies at this station usually keep to their little packs,” Hanamaki says.

“Well, that’s bullshit,” Iwaizumi replies. Oikawa can’t stop the grin or snort of laughter that bubbles up in his throat. “At my last station, soldiers worked with scientists and engineers to throw around ideas for projects. This place is so divided. I don’t know how you get anything done.”

“We’re all really good at what we do—that’s how,” Matsukawa says, like that should be obvious.

“Doesn’t mean you can’t be better as a team,” Iwaizumi replies.

Matsukawa tilts his head to the side, conceding that Iwaizumi may have a point.

“How much shit do you think you’re going to get from your squad for sitting with me?” Oikawa asks. He puts on a practiced smile and waves at Zeta Squad, most of whom looks away, a few others hesitantly waving back.

Iwaizumi grins. “Not as much shit as your guys are going to give you when I kick your ass later in training.”

“Excuse me?”

“C’mon, how often do you science guys spare? What if the station is attacked? You have to know how to defend yourselves or you’re as good as useless.”

“I don’t know how sparing is going to help when the enemy has guns and psionic powers,” Oikawa says dryly.

“Ah, yes, Mr. Sectoid, please punch me so I may punch you back,” Matsukawa says overdramatically. “No, no, don’t use your psionic powers, that’s against the rules!”

Iwaizumi laughs. “Okay, so maybe you can’t throw down with an alien.”

“Speak for yourself,” Hanamaki says, holding his fists up like a boxer. “I want to fight a Muton.”

Iwaizumi grins and goes on, “But maybe some of those guys that talk shit about you might shut up if they know you can hit back with more than sly smiles and annoying paperwork.”

Oikawa hums, considering this.

“That would be nice,” Hanamaki says. “I swear, the amount of times I’ve had to restraint myself when I hear people talk bad about you, Boss.”

Matsukawa snorts. “Bull. Shit. You started half those rumors and Oikawa knows it.”

“So maybe I was a little disgruntled after three seventeen-hour days in a row. Sue me.”

Oikawa rolls his eyes.

“Well?” Iwaizumi prompts. “What do you say, Doc?”

No way in hell Oikawa is going to turn down a challenge.

“Fine. But I pick the time.”

 

* * *

 

Oikawa waits a week before contacting Iwaizumi through the interface found in every room in the station. You can send messages and control the room’s setting like the lights and A/C through the interface. Oikawa gets a response after dinner.

_21:00 gym 4 room 1_

That night he changes into a tight-fitting compression shirt and looser pants and makes his way to the room at 21:00 sharp. There are always squaddies in the gym and Oikawa isn’t eager to spare in public, but it seems Iwaizumi reserved a small room for them to spare in. There are mats along the floor and mirrors on the wall and though the air is filtered, it still smells like stale sweat.

Iwaizumi is waiting in the center of the room, stretching on the mats. He’s standing, one leg bent behind him, a hand around his ankle as he pulls the leg towards his back, the heel of his foot nearly touching his back. His outfit is the opposite of Oikawa’s—loose shirt and tight, tight pants that cling to him like a second skin.

The soldier grins when he spots Oikawa.

“Ready to kick my ass?” Iwaizumi taunts.

“You won’t be so cocky when we’re done,” Oikawa replies, moving to stand a few feet away and begin his own stretches.

Iwaizumi laughs. “I’m looking forward to it.”

They’re both quiet, not bothering with awkward small talk, and the air in the room begins to grow heavier. Not physically heavier, but in feeling, heavier with anticipation.

When they’re both done, they face each other, neither panting or sweating, but they’re both tense with adrenaline and anticipation.

“Rules?” Oikawa asks, keeping his voice impartial and calm.

“No going for the eyes or groin,” Iwaizumi replies. “First one to pin the other wins.”

Oikawa nods, agreeing to the rules.

Then Iwaizumi is charging him headfirst. Oikawa doesn’t have a lot of experience in hand to hand combat—he did train with a pistol as part of his introduction to the station and he was a crack shot, but there’s a big difference between hitting a stationary target and what a soldier like Iwaizumi does.

Iwaizumi fights hard and fast, his moves obvious, but he doesn’t need to hide his intent. He’s fast and strong, even for an alpha, and Oikawa is on the defensive fighting for a chance to change the tide.

When Iwaizumi ducks down and sweeps a leg out, knocking Oikawa off his feet, Oikawa grabs his ankle and pulls him down with him. They tumble along the matts, grappling. One second, Iwaizumi is under him, the next, Iwaizumi is above him. They turn and turn, almost making Oikawa dizzy, before Iwaizumi wraps his legs around Oikawa’s waist and slams him hard to the side, head hitting the mat with enough force to make his ears ring.

Disoriented, Oikawa hardly notices Iwaizumi rolling him onto his back, thighs tight on his hips, preventing him from getting any real leverage. Iwaizumi grabs his wrists and Oikawa struggles, by no means weak, but Iwaizumi still gets his wrists pinned far above his head.

Iwaizumi is so close like this. Oikawa could headbutt him if he was just an inch or two closer. This close, Oikawa can smell him. It’s sharp and sour, the scent of another alpha whose blood is coursing with adrenaline, and it burns his nose.

Oikawa growls and thrashes, trying to break the hold, but Iwaizumi’s weight is heavy on his hips and kicking his legs isn’t getting him anywhere. He wonders how long Iwaizumi will make him struggle before asking if he submits. Alpha’s always get a rush hearing they’ve beaten another alpha. Oikawa snarls at the thought.

But Iwaizumi doesn’t say anything. He stands up, holding out his hand, and Oikawa takes it. On his feet, he stares at Iwaizumi, trying to figure out what he's thinking.

“Again,” Oikawa pants.

Iwaizumi takes his stance.

 

* * *

 

After a few more rounds—Oikawa manages to pin Iwaizumi once and he’s surprised to see Iwaizumi is smiling almost as wide as he is—they pack it up and go to the showers. Oikawa has a private bathroom as a department head, but he doesn’t want to walk around the station smelling like sweat and alpha. He doesn’t like to make anyone uncomfortable with his scent if he can avoid it, especially the many omegas that work in his department.

The showers are open and don’t have curtains or walls, just a row of shower heads. No one is showering this late at night, leaving them alone in the room, each noise echoing in the emptiness. Near the showerheads, there are hooks for towels and small rationed bottles of all-in-one soap for people to use.

Oikawa strips and turns on the water for the first showerhead he sees, spreading the soap through his wet hair and along his skin. Iwaizumi puts an empty showerhead between them as a sort of buffer, but he’s still within sight and Oikawa is not dumb. He can see Iwaizumi’s head turn slightly to look at him more than once, so obvious in intent.

“I can only think of two reasons for why you’re looking at my ass,” Oikawa says. Iwaizumi’s eyes slowly rise to meet Oikawa’s, like he’s enjoying the entirety of Oikawa’s body and not just his ass. Oikawa raises two fingers and Iwaizumi arches an eyebrow in question. “One, I have a fantastic ass and you’re jealous, as you should be. Two, you want to know if I’m an omega and you’re actually looking at my cock, which is also fantastic, by the way.”

Iwaizumi rolls his eyes and looks away, returning to washing his body. Oikawa has never doubted that Iwaizumi is an alpha. He is the picture-perfect definition of one, except for perhaps the height.

“I’m an alpha, in case you couldn’t smell me earlier,” Oikawa goes on, “so you can stop looking.”

“Why would I stop looking just because you’re an alpha?” Iwaizumi asks without so much as glancing at him.

Oikawa’s voice dies in his throat.

Are you gay? he wants to ask but doesn’t because it just seems rude. He doesn’t want to give Iwaizumi the impression that he cares about that sort of thing. Maybe he should say that instead, that he doesn’t care if Iwaizumi likes other alphas, but he doesn’t so move along.

Oikawa doesn’t say anything and Iwaizumi doesn’t look again.

 

* * *

 

Training, somehow, becomes a regular thing between Oikawa and Iwaizumi. At least twice a week they meet and tumble on the mats, fighting for dominance. Iwaizumi shows him how to throw a proper punch without breaking his thumb and a few ways to break out of holds, and Oikawa shows him alien organs.

Okay, so maybe one isn’t like the other, but when Iwaizumi starts showing up at Oikawa’s lab on a regular basis, Oikawa shows him what he does. A lot of it is boring to Iwaizumi, who sits next to him anyways and they talk while he works about anything and everything. Talking to him is surprisingly easy.

Oikawa is getting better at sparring, more used to how Iwaizumi moves. He lands more hits and pins him almost half the time. Iwaizumi grins every time, like he doesn’t mind submitting, and Oikawa doesn’t get how he can stand it.

But this is not a time when Oikawa pins him.

This time, Iwaizumi pins him, straddling his waist, hands pinned above his head, similar to the first time Iwaizumi had pinned him. Only Iwaizumi doesn’t let up. He stays there, practically sitting on Oikawa’s hips, heavy and hard and unmoving, just staring at Oikawa.

“What are you looking at?” Oikawa asks, panting and trying to break out of Iwaizumi’s hold. He never gives up, not until Iwaizumi decides he is defeated. He fights until the end.

Iwaizumi’s face is surprisingly soft. “You.”

One second, Iwaizumi has him pinned to the ground and Oikawa is struggling to get loose and the next, Iwaizumi is bent over him, lips on the corner of his mouth in the briefest of kisses.

Oikawa freezes in shock, his body stilling, and Iwaizumi’s lips move front and center.

It’s not the kiss Oikawa expects. He expects rough and hard, tongue so deep in his mouth that he can’t think straight and lips so firm they have no softness to them. What he gets is the opposite. He gets Iwaizumi’s lips dryly pressing against his own, shifting slightly, no trace of his tongue where his heavy alpha taste rests.

His lips may be gentle, but that does not mean there is no passion. He can feel Iwaizumi press down against him, lining their bodies up. Iwaizumi’s hands move from their hold on his wrists, one curling around his skull to cushion his head from the mat, the other bracing somewhere near his ear. His entire body is tight with arousal over Oikawa, _because_ of Oikawa.

Oikawa moans into the kiss, tilting his head to get a better angle and that makes Iwaizumi smile against his lips. Oikawa’s hands thread into Iwaizumi’s short sweaty hair, sliding along his scalp, nails dragging and scratching as he goes, and that makes Iwaizumi groan in a way that has Oikawa’s blood rushing south. He likes it rough, Oikawa realizes and he can't say he doesn't like the same.

Iwaizumi’s hand moves away from the back of his skull, dragging down his chest to his groin where he gropes for Oikawa’s cock. The room smells of stale sweet and alpha and Oikawa shouldn’t be as turned on as he is, but he can’t help the way his hips rise to meet Iwaizumi’s hand or the way his cock responds when Iwaizumi rubs the heel of his hand over Oikawa’s length. He's quickly filling out with blood, growing harder and harder as Iwaizumi rubs and rubs.

“Is this okay?” Iwaizumi asks, kissing a line across Oikawa’s cheek to beneath his ear.

Oikawa gasps for two reasons. One, there is a very strong, very firm hand rubbing at the length of his cock and it has been ages since Oikawa had another person touch him. And two, Iwaizumi is asking permission.

Oikawa has always heard that gay alphas are rough. That when you put two alphas together, they’re always going to fight. Oikawa has experienced it first hand with soldiers that hate submitting to Oikawa’s expertise and position. Hell, Iwaizumi and he have been fighting at least twice a week for three weeks now. He’s always had this image in his head of gay alphas fucking hard and fast with lots of scratching and shoving and blood.

This is not like that. This is…

Oikawa doesn’t know what this is.

He doesn’t know and he panics. He flips their positions, pinning Iwaizumi under him, all of his weight settled on Iwaizumi’s hips, their bodies lined up just right so Oikawa can feel Iwaizumi’s hard cock pressing against his own. He’s got his hands wrapped around Iwaizumi’s wrists and his hands pinned above his head, his body lying between his thighs. Iwaizumi isn’t soft and sweet-smelling like a pretty faced omega, but the familiarity of being on top, of being in control, calms Oikawa. 

Iwaizumi grins at Oikawa’s display of dominance and control like it’s the hottest fucking thing he’s ever seen. Why isn’t he fighting back, trying to get back on top? Oikawa’s entire body screams at him when he’s under someone as strong as him. Does Iwaizumi see him as weak? Is that why he’s able to lie there and let Oikawa hold him down? Or is there another reason? 

“What are you going to do now?” Iwaizumi taunts. Oikawa's weight isn't placed right; he could flip them so easily, but he doesn't, like he wants to be beneath Oikawa. “Or are you just going to keep staring at me like a deer in headlights?”

Oikawa focuses on his breathing and tries to piece his thoughts together. What does he want? Does he want this? He’s never wanted another alpha beneath him. Iwaizumi isn’t anything like an omega or even a beta; he’s all sharp angles and hard muscles and strong sharp scent. Even through their clothes, Oikawa can tell his cock is so _big_ , just about Oikawa’s size, an alpha’s cock, and Oikawa can’t say he isn’t curious what that would feel like in his hand, how hot their flesh would feel pressed together.

Iwaizumi may be an alpha, but he’s hot and he’s willing and he’s grinning like he’s waiting for Oikawa to make the next move and Oikawa is so turned on he can’t fucking think.

“C’mon,” Iwaizumi says, growing impatient, but his tone is still playful and light. He tries to press his hips up, trying to get friction, but doesn’t get much. “Does that big dick of yours actually work or is it just for show?”

Oikawa growls, irritated, and tightens his grip on his wrists as he leans down to bite his neck. Iwaizumi tilts his head back into it, baring his throat, and groans when Oikawa makes his way up to his scent gland. He’s so used to kissing omegas under their ears and tasting something sweet, but when he licks Iwaizumi, he gets a mouthful of strong alpha. It’s sharp and overwhelming, like sticking his tongue in cologne.

He reels back, gagging, and Iwaizumi softly laughs at him.

“First time with an alpha?” Iwaizumi asks and it might be genuine concern, or a light-hearted joke, but Oikawa just feels like he’s being mocked.

Oikawa shifts his hips and grinds down hard against Iwaizumi’s to shut him up. He can feel the slow drag of Iwaizumi’s cock against his hip.

“ _Fuck_ ,” Iwaizumi curses sharply, head tossed back and hips pressing up to meet Oikawa’s. Their cocks slide right along one another and both of them moan out in pleasure at the slow, hard drag.

Iwaizumi’s face is twisted up in a way Oikawa could never imagine to be sexy on an alpha but it is, eyebrows pushed together and eyes closed and jaw dropped like he’s about to moan. How is Iwaizumi so hot?

Oikawa is so, so screwed.

He’s never felt such a large cock against his own. He wonders what it’d feel like skin to skin, cock to cock. Could he even wrap his hand around both of them? He doubts it, but he wants to try, wants to fuck down against Iwaizumi’s cock and make him come all over himself and then mark him with his own cum. Iwaizumi’s torso is already a work of art. Covering it cum would only make it look better. He'd look so good drenched in Oikawa's cum. 

Oikawa leans down and kisses him on the mouth, rougher and messier than Iwaizumi had kissed him. When Iwaizumi’s tongue presses against his own, he fights the urge to gag so that he can kiss back. His taste isn’t as strong than it had been on his neck but it’s still there. It’s easy to distract himself with their cocks line up just right between their bodies, rubbing hot and hard through the thin fabric of their workout clothes.

Iwaizumi’s arms and hands begin to struggle until they break out of Oikawa’s hold, but he doesn’t flip them like Oikawa thought he would. Instead his hands find Oikawa’s ass and kneads into the flesh there. He spreads his legs to give Oikawa more room to work and he helps Oikawa rock down, urging him to move faster.

Oikawa gasps. How does this feel so fucking good?

Iwaizumi leans up to lick at Oikawa’s neck, breathing in his scent and licking him like his taste is fine cuisine. Iwaizumi is definitely getting off on his scent and taste, not gagging at all like Oikawa had.

Oikawa’s mind begins to wonder how that’s possible, biologically speaking. The vomeronasal organ in alpha’s has receptors for omega pheromones, not alpha pheromones. Does Iwaizumi have some genetic condition that makes him express receptors to alpha pheromones as well? There can’t be any other explanation. Other than maybe he likes the smell in taste, in a non-pheromonal way, which Oikawa just doesn’t get because he had gagged from Iwaizumi’s scent. Did Iwaizumi train himself to overcome it, or maybe he was just used to it? How many alphas did he have to fuck before getting to this point?

Iwaizumi is grinding against him good now and licking at all the right spots on his neck and Oikawa gasps, coming out of his head and back to his body. And right now, he is very close to coming in his pants like a teenager.

The drag of his cock again Iwaizumi’s is so good and even through their layers he can feel the heat of his cock pressed up against his own. Oikawa rubs down against him harder and faster and Iwaizumi gasps then bites into his neck. Oikawa hisses through his teeth, nostrils flaring, the flood of emotions and confusion drowned out by good, good, so fucking _good_.

Iwaizumi plants his feet on the ground and starts grinding up against Oikawa, giving as good as he gets. Oikawa comes with a harsh moan, feeling like the air’s been punched from his lungs. He stills, trembling and oversensitive, but Iwaizumi’s hips are still working beneath him, his cock still hard and aching for its own release.

When he stills his hips, Iwaizumi growls in frustration and flips him onto his back, shoving one of Oikawa’s legs between his thighs and riding him hard and fast and dirty. Oikawa doesn’t know what to do as Iwaizumi lies on top of him, riding his leg like it’s the best damn thing, his lips making a mess of the scent glands on Oikawa’s neck. He lies there, sedated and exhausted, and lets Iwaizumi use his body until he tips over the edge, groaning deeply when he comes.

Iwaizumi kisses him and Oikawa hardly flinches at the taste this time around. Iwaizumi’s kiss is lazy with his orgasm, a slow tug of lips that Oikawa actually enjoys. He rolls off of Oikawa eventually and gets to his feet, running a hand through his sweaty hair. 

“We should shower,” Iwaizumi says, almost detached.

Oikawa’s jaw shifts, annoyed, as he sits up and adjusts his softening cock in his pants. “This is never going to happen again.”

Iwaizumi looks down at him and doesn’t look like he believes him for a second.

“I’m serious,” Oikawa says.

Iwaizumi holds up his hands. “Okay. It won’t happen again.”


	2. Chapter 2

It happens again.

Iwaizumi keeps his distance for over a week, giving Oikawa space to process what happened, but after inviting himself to sit with Oikawa and his team at lunch, and sending him a message on the interface asking to spare, Oikawa realizes he should just act like he did before, like nothing happened, just like Iwaizumi is.

So he sits at lunch and laughs with the man who made him come his brains out and spars with him at night until they’re both drenched in sweat and panting, covered in each other’s scent.

And it works until it doesn’t.

Because Oikawa can’t forget the sharp taste of Iwaizumi’s sweat, or the feeling of the man under him, or how good Iwaizumi looked riding his leg until he came. He wants to see more, taste more, _feel_ more and he hates himself for it.

He shouldn’t feel like this. He’s not gay. He’s never in his life been attracted to another alpha. Why is Iwaizumi so different? He tries to rationalize it, tries to tell himself it’s just because it’s been awhile since he’s been with another person he feels so comfortable around, that he craves intimacy, not the man. But somehow, he knows that isn’t true.

After a rather intense sparing session that ended with grappling on the floor, tumbling over each other to get on top, legs around waists and heads under armpits and sweaty skin on sweaty skin, Oikawa is ashamed. Not only had Iwaizumi pinned him in the end, but he’s halfway to hard in his pants.

He tries to hide it, putting his back to Iwaizumi as he showers. There’s always a one stall buffer between them, but Iwaizumi is fucking perceptive.

“You want some help taking care of that?” Iwaizumi asks casually and when Oikawa looks over, the bastard isn’t even looking at him, just soaping up his body, his damn massive cock frustratingly soft between his thighs.

So now Oikawa gets turned on wrestling with a sweaty alpha, but the gay alpha doesn’t? _Fantastic_.

“I’ve been working a lot is all,” Oikawa replies coolly. Two can play at this game. He can be indifferent, too. “Unlike you, I have a private room.”

Iwaizumi shorts. “You sure that’s what you want?”

“Sounds like you want it more than me.”

“Yeah, I want it—I want you,” Iwaizumi says bluntly, not an ounce of shame, voice so thick Oikawa could drown in it. He walks over, stepping out of the spray of his own shower and walking under Oikawa’s. “And I know you want me to touch you, too, but I need to hear you say it before I wreck you again.”

“You’re way too cocky for someone that humped my leg.” Oikawa backs against the wall and Iwaizumi presses in, following, close but still not touching.

“And you’re way too stubborn.”

He leans forward, pressing his face into Oikawa’s neck, nosing at his scent gland and teasing his lips over his neck, not pressing hard enough for him to really feel it or get any pleasure out of it, but god, he wants it. He wants it hard and fast and a little nasty and he fucking hates himself for it.

“All you have to do is say it. C’mon. Say you want it and I’ll touch you. Or, say you don’t and I’ll go away, I promise, and I’ll never ask or say anything again.”

Oikawa’s jaw shifts.

“I want it,” he says begrudgingly, hating himself for it.

The second he says it, Iwaizumi shoves him against the shower wall and bites at his neck. Not hard, not even enough to leave a mark, but enough to let Oikawa feel his teeth and the wet slide of his tongue after to sooth away the pain.

Oikawa groans.

“Fuck, yeah,” Iwaizumi murmurs, pressing forward, slotting his hips against Oikawa’s. “That’s it. Just relax and let me take care of it.”

Iwaizumi wasn’t hard before, but he’s getting there, thick and hot against Oikawa’s own cock. Oikawa desperately wants to know which one of them is bigger, needing some sort of leverage. He needs to win, needs to dominate, and wonders why these primal emotions are coming up now. He has never been a picture-perfect alpha. He’s an academic, not a soldier. A speaker, not a fighter. But with Iwaizumi, the alpha in him comes out.

He needs some sort of superiority, but all he gets is Iwaizumi kissing him and sliding a hand down between their bodies to wrap around Oikawa’s length. It feels so good to have another person’s hand on him. He can’t remember the last time someone else touched him. Even during that first initial accident with Iwaizumi, all they did was rub and thrust against one another through a barrier of fabric. Having a strong, calloused hand wrap around his length and twist over his head is far better.

It’s been so damn long since he had someone touch him directly and he’s never had an alpha cock against his. It’s not any hotter in temperature, but the size and girth are larger than anything he’s dealt with. Even the betas he’s slept with didn’t have cocks like Iwaizumi’s, hard and thick and rubbing against him from root to tip in a way nothing else ever had.

Oikawa’s head tilts back against the wall and he rises to the tips of his toes as Iwaizumi sucks at the scent gland under his ear, the scent and taste dampened by the water. Oikawa can only pray no one comes in and sees them like this. There are no walls, no curtains. Anyone that came in would have a front row view of Iwaizumi’s wet ass and his hand around Oikawa’s cock.

“God, I’ve never really cared what my partner has, but you’ve got a nice cock,” Iwaizumi murmurs as he strokes him from root to tip. Oikawa groans. Iwaizumi grins against his skin. “You got a thing for dirty talk?”

Just your voice, Oikawa thinks but he’ll be damned if he says that.

“Shut up,” Oikawa gasps.

He tucks his head to the side, getting a face full of Iwaizumi’s neck and he can smell him even through the water. Sharp and strong and unavoidable, it soaks into his lungs and makes his head dizzy. Is this how omegas feel? It’s impossible. He doesn’t have the pheromone receptors they do. It’s not even a good scent. It’s just overbearing, almost too strong, but he can’t get enough of it.

Iwaizumi’s other hand comes up and grabs a fistful of his hair, tilting his head back and away, baring his throat for Iwaizumi to continue what Oikawa can only describe an attack on his neck. Kissing, licking, sucking—whatever skin he can touch, he is, and Oikawa can feel his toes tingling with it.

When he comes, it’s because Iwaizumi bites down on his scent gland, pushing him violently over the edge.

“Yeah, that’s it,” Iwaizumi murmurs as Oikawa moans again and again, fucking into Iwaizumi’s hand, Iwaizumi stroking him through it.

Even as his orgasm ebbs, Iwaizumi doesn’t stop, stroking him harder and firmer and Oikawa can’t decide if he wants to fuck into it or twist away because it’s too much. Then, Iwaizumi hand moves lower, pressing at his knot.

His goddamn _knot_. When did that happen?

“Fuck, fuck, fuck,” Oikawa curses in quick succession, each higher in pitch than the last. He manages to look down between their bodies and sees what he’s feeling. “I’ve never—holy shit, _how_ —”

“Never knotted outside of fucking before, huh?” Iwaizumi figures, voice surprisingly calm.

Oikawa shakes his head.

He wraps his arms around Iwaizumi’s neck, needing something to hold onto. He’s felt his knot squeezed by people’s bodies when he’s buried deep inside, but it’s a far different sensation from strong, prodding fingers that rub underneath and squeeze as they stroke upwards. When he’s inside someone, they clench at the base of his knot, their body tight and hot but not like this. Iwaizumi’s fingers press just right, putting pressure on places Oikawa didn’t know could feel so good, so sensitive.

Oikawa thrusts his hips forward, chasing the sensation.

“Gonna come again?” Iwaizumi asks and Oikawa honestly doesn’t know. He’s never felt this, never knew he could feel this from just a hand on his knot. Hell, he didn’t even know he was capable of knotting outside of penetration.

Why does this feel so damn good? It’s so fucking hot, it makes his legs shake. His entire body is on fire, tight with tension, balls drawn up on the verge of an orgasm he didn’t know he was capable of having.

Iwaizumi leans forward and nips at Oikawa’s neck, murmuring into his skin, “C’mon. Come all over my hand. Get me _wet_.”

Oikawa doesn’t know what he means, thinking it’s just some cheesy line he uses, until Iwaizumi squeezes his knot nice and firm and he comes a second time. He’s come twice before, but not like this. Not so soon. Not when his cock is going soft and he’s knotted. He’s never come from his fucking knot either. This is deeper, hotter, like his body is an open nerve, his cock and knot on fire. It makes him fucking mindless; all he can think about is how damn good it feels.

His comes and his cock _leaks_ as Iwaizumi licks his neck with long, slow swipes of his tongue. Thin slick fluid not entirely unlike cum gushes out the head of his half-soft cock, drenching Iwaizumi’s hand. Oikawa stares between their bodies, at Iwaizumi’s dark hand wrapped around his cock, at the unending slick wetness running down to his wrist, drenching him, getting him _wet_ , just like he said, just like he wanted.

He’s never had that happen before. Male alphas produce more ejaculate when the knot, but it’s not as thick as usual semen and it usually just gets reabsorbed into the body. Oikawa’s never actually come, even when his knot has been squeezed by a hot, tight omega. Somehow, whatever Iwaizumi is doing to him is making him come again and again and again without ever stopping and it feels so fucking _good_.

“Holy fuck,” Oikawa gasps, breathless. He wants to whine, wants to moan, wants to beg for more, more, _more_. “What are you doing to me?”

Iwaizumi chuckles, amused. “I can’t believe you’ve never rubbed your knot. Where’s your scientific curiosity, Doc?”

Oikawa groans as he watches, wondering when it’s going to stop, if it’s every going to stop, if he’s going to be a trembling mess forever and Iwaizumi is just going to have to follow him around with a hand in his pants because he doesn’t want it to stop, wants to feel this forever.

It does stop, eventually, and Iwaizumi bring his hand up to lick at it. Oikawa watches, torn between disgust and unbridled lust. Iwaizumi sucks at his fingers and wrist, laps at his palm with his tongue, cleaning his hand of the thin sticky fluid.

Oikawa slides his arms from around Iwaizumi’s neck and without something to hold onto, he falls to his knees in front of Iwaizumi, who is achingly hard.

“You okay?” Iwaizumi asks urgently.

He feels like an idiot. A fucked-out idiot that just came twice because of another alpha. His pride is screaming at him, embarrassment and shame growing hot in his gut as he stares at Iwaizumi’s erection. He needs to get back in control, somehow.

Panting and trembling, Oikawa reaches out and grips Iwaizumi’s cock. He parts his lips and flicks his eyes up to meet Iwaizumi’s gaze, wondering if this is okay.

Iwaizumi’s hand reaches down and cradles his jaw, the touch surprisingly gentle. “You don’t have to do this. You don’t have to prove anything to me.”

Oikawa turns his head to the side and brings Iwaizumi’s thumb into his mouth, swirling his tongue around the digit and tasting himself before releasing it with a grin when he sees Iwaizumi’s desperate expression. Somehow, knowing Iwaizumi is as turned on and wrecked as he is makes it less embarrassing that his knees gave out like an omega in heat, less embarrassing that he came twice, less embarrassing that he came because someone rubbed his damn knot.

“I want to,” Oikawa says and he means it.

He hopes he doesn’t come across even half as desperate for it as he is. He doesn’t know why, but he wants to suck this man’s cock, this _alpha’s_ cock. He wants it so bad it almost hurts. Maybe it’s his pride pushing him. Maybe it’s not. He doesn’t care. He wants to suck his cock and make him come.

“And in the shower, you don’t smell as bad,” Oikawa adds lightly.

“Are you saying I stink?” Iwaizumi asks with a playful grin, fully understanding what Oikawa means. Iwaizumi smells like an alpha and last time, Oikawa had gagged so hard he almost threw up, and he hadn’t been anywhere near his cock then.

Iwaizumi moves his hand around to cradle the back of Oikawa’s head, the curve of his palm fitting perfectly to his skull. Oikawa shivers at the touch.

“If it’s too much, pull back,” Iwaizumi says in a soft voice that makes Oikawa melt. “I don’t want you gagging on my cock from the smell or the size. I don’t get off on people being uncomfortable.”

“Don’t get cocky.” Oikawa gives him his best shit eating grin. “You’re not _that_ big.”

Iwaizumi laughs until Oikawa leans forward and licks at the head of his cock. Then, his laughter turns into a quiet gasp, his fingers curling gently into Oikawa’s hair.

Oikawa is not an alpha that takes without giving. All the betas and omegas he’s slept with have gotten more than his cock in them when he sleeps with them. He gives as good as he gets, not stopping until he is sure they are satisfied, whether that means fucking through the night or blowing them after with his fingers deep inside them. He briefly wonders if Iwaizumi’s ever taken a cock, if he would let Oikawa slide his fingers in, how tight he may or may not be.

Alphas can take a cock, but it’s not easy. Even female alphas have difficulties taking another alpha’s cock. Children of two alphas are so rare they’re almost unheard of; they’re considered medical anomalies.

Iwaizumi’s length is a larger than other’s he’s dealt with and the alpha scent is impossible to ignore, but it is dampened by the water and humid air of the shower. Oikawa doesn’t even gag when he takes the head into his mouth, he notes with pride, tonguing at the slit and underside. One hand holds him at the base, the other curled around his hip, fingers pressing in hard in the way he thinks Iwaizumi likes. If he doesn’t like it, he doesn’t pry Oikawa’s hand off or say anything.

He takes his time, pushing his jaw further down as he takes Iwaizumi deeper into his mouth. He can’t take all of him. He isn’t crazy. He just wants to make him come, wants to make his legs shake so he doesn’t feel as bad about collapsing like some virgin. He wants to show Iwaizumi that he gives as good as he gets, that he gives _better_.

Both of Iwaizumi’s hands find their way into Oikawa’s hair, not tugging, just following his motion, fingers gentle against his scalp. Oikawa looks up at him and Iwaizumi looks back, eyes hot and blown out with lust.

“Fuck,” Iwaizumi gasps when their eyes lock, unmoving from each other. “Fuck, you look so good right now.”

Oikawa moans around his cock and Iwaizumi’s head tilts back, breaking their eye contact, but Oikawa still looks, unable to look away from the tight tension in his neck or the hard planes of his tanned stomach. Eventually, though, his eyes burn, and he focuses on the task at hand, closing his eyes and working his head faster, Iwaizumi’s fingers tightening in his hair.

“Can I come in your mouth?” Iwaizumi grunts, voice tight. Oikawa moans around his cock again, not stopping, and Iwaizumi curls forward slightly. “If you don’t want me to, you need to pull off now.”

For a second, Oikawa considers pulling off, but he doesn’t. He presses forward, trying to get him just a fraction deeper, and when he pulls back, Iwaizumi comes.

The taste is so fucking strong. He retches, his mouth filling with saliva, his abdomen twisting in warning. He wants so badly to swallow it, to open his mouth and show Iwaizumi that he could do it, that he took it and took it well, but his body doesn’t agree. Something about having another alpha’s cum in his mouth is making him violently, instinctually ill.

Oikawa pulls off his cock and closes his mouth, unable to swallow but knowing that if he tries to spit it out, he may vomit. He shoves the back of his hand against his mouth and looks up at Iwaizumi, his eyes wide with panic and hopes Iwaizumi can tell something’s wrong because he can’t talk. 

“You’re okay,” Iwaizumi says in a gentle tone. He urges Oikawa up as quickly as he can without hurting him and kisses the corner of his mouth. “Give it to me. C’mon. Just open your mouth.”

Oikawa opens his mouth a fraction of an inch and Iwaizumi’s tongue opens it the rest. Oikawa doesn’t know whether he’s supposed to keep his lips still or kiss back as Iwaizumi’s tongue licks his own cum out of his mouth. Even when Iwaizumi is done, Oikawa’s mouth is soaked with his taste.

“Better?” Iwaizumi asks, kissing across his cheek to his ear.

Oikawa’s face scrunches up, the taste still lingering. “I still want mouthwash.”

Iwaizumi laughs. He presses his nose beneath Oikawa’s ear, breathing in deeps, and murmurs, “You did so well. You felt so fucking good.”

“I’m not some dog to be praised,” Oikawa complains without any real venom.

Iwaizumi remains gentle, kissing his hair. “I know. I love that about you.”

Oikawa can almost imagine his smile.

**Notes for the Chapter:**

> It's been over half a year, but believe it or not, I did not forget about this fic. I just lost inspiration. But I've have this scene written and maybe posting will make me want to finish it up? (There's still a lot I want to do/include. Most of it sex. This entire fic is mostly sex with feelings lol.)


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